Aerosol product and method for manufacturing the same

ABSTRACT

An aerosol product comprising a double-chamber container separated by a movable partition capable of dividing contents therewith, one spatial portion thereof being loaded with contents to be discharged and the other spatial portion being loaded with compressed gas for pressurizing. The compressed gas is a mixed compressed gas of at least two types of mixed gas, at least a part of the partition presents permeability of the compressed gas, and the mixed compressed gas selectively permeates the partition to be dissolved in the contents to be ready for discharge.

TECHNICAL FIELD

The present invention relates to an aerosol product. More particularly,the present invention relates to an aerosol product of which internalpressure is made low and which can be easily manufactured, and a methodfor manufacturing the same. The present invention also relates to anaerosol product wherein a loading amount of contents can be increasedthan compared to conventional products.

BACKGROUND ART

For spraying contents of an aerosol product in a form of fine foggyparticles or discharging contents in a foamed condition, it wasconventionally the case that compressed gas such as carbonic acid gas(CO₂) was filled into an aerosol container as a propellant to bedissolved within the contents.

For making the compressed gas dissolve within the contents, a specifiedamount of contents is first loaded into the container and compressed gasis then loaded into the container at a high pressure. Since thecompressed gas is dissolved into the concentrate (contents), it isnecessary to apply a high pressure exceeding an internal pressure of thefinal aerosol product in an equilibrium state.

Explanations will now be given based on a case of a general aerosolproduct containing therein compressed gas having an Ostwald absorptioncoefficient (hereinafter referred to as simply “Ostwald coefficient”) of1 as well as contents and wherein the volumetric ratio of the contentsis approximately 60% and the volumetric ratio of the compressed gasapproximately 40% of the total capacity of the container in case aninternal pressure within the container is 0.6 MPa (hereinafter all givenas gauge pressure).

As referred herein, the Ostwald coefficient simply represents numericvalues of a gaseous volume (ml) dissolved in 1 ml of solvent attemperature t° C. in case a partial pressure of the gas is set to 760mmHg. In case the temperature is identical, the dissolution ratio isproportional to pressure.

Hence, it is necessary to first inject contents into the containercorresponding to approximately 60% by volume under atmospheric pressure,followed by injection of compressed gas of 1.5 MPa. A pressure P of gasto be injected and corresponding to 40% by volume based on anequilibrium pressure within the container of 0.6 MPa (40% by volume ofcompressed gas and 60% by volume of aerosol) is given by the equation

P×0.4=0.6×0.4+(0.6×0.6)×1,

so that the above value of 1.5 MPa can be obtained. As a generalformula, the following equation (1) can be obtained.

P ₁ =P ₂×{χ+β(1−χ)/χ  (1)

While it is presupposed in this equation that the compressed gas doesnot dissolve into the contents until the loading of the compressed gasis completed, the compressed gas actually starts to slightly dissolvewithin the contents during the loading process so that a maximumpressure in the above case is slightly less than 1.5 MPa andapproximately 1.4 MPa.

However, conventional aerosol containers can generally not bear evensuch a degree of pressure. Even if a container should bear thispressure, drawbacks are caused such that a fixing (crimp) of an aerosolvalve become loosened. In case of using a container capable of bearingsuch a high pressure, manufacturing costs will remarkably increase.

Therefore, it is conventionally performed that a separate large sizedpressure resistant container is used for the manufacture of aerosolliquid which is sequentially loaded into individual aerosol containers.This method still presents drawbacks in that facilities costs will belargely increased and is also accompanied by increased number of stepsduring manufacturing.

In a conventional aerosol product using a single-walled can forcompressed gas products, the interior pressure of the containergradually decreases each time spraying of the contents is performed.Accompanying this, the amount of dissolved compressed gas is alsodecreased whereby it becomes difficult to maintain an action of makingthe foggy particles of the contents fine. Due to this reason, it isrequired to set the initial pressure as well as the loading rate for thegas high.

In the case a false operation (e.g. the product is used in an invertedposture while the specification prescribes that it should be used in anerected posture), only gas is sprayed so that the pressure of theproduct is remarkably decreased. It is known for conventional methodsfor solving this problem wherein a weight is provided at a tip of a tubeprovided at a valve, while this method is not very reliable due toreasons that the weight might not work in a sufficient manner.

It has then been proposed for an aerosol product with the aim of solvingthis problem as disclosed in Japanese Unexamined Patent Publication No.253408/1996 utilizing a double-chamber container including an innercylinder and an outer cylinder with which it is aimed to restrictdecreases in the amount of dissolved compressed gas accompanying theincrease in number of spraying.

In this aerosol product utilizing a double-chamber container, thecontents are loaded into the interior of the inner cylinder whilecompressed gas is dissolved into the contents, and a spatial portionbetween the inner cylinder and the outer cylinder is loaded withcompressed gas as a pressurizing agent such as liquefied petroleum gas(LPG) or nitrogen. Since the inner cylinder is a flexible sack-like bodymade of synthetic resin or the like, the inner cylinder is shrunk by thepressure applied by the pressurizing agent even if the contents includedin the inner cylinder is used to be decreased, so that it can beprevented that the amount of compressed gas dissolved in the contents isdecreased.

There are mainly two methods for loading compressed gas into thedouble-chamber container. In a former method that is a so-called TNloading method, the contents (concentrate) are loaded into the innercylinder, and a valve is crimped to the outer cylinder. Then, compressedgas to be dissolved into the contents is loaded into the inner cylinderfrom a stem of the valve. Thereafter, compressed gas for depressing theinner cylinder is loaded through a bottom plug of the outer cylinder.

In a latter method, a spray valve is first crimped to the outer cylinderin case of employing a double-chamber container provided with a checkvalve at a bottom portion of the inner cylinder permitting only flow ofgas from the inner cylinder into the outer cylinder (while the flow ofcontents is not permitted). Then, compressed gas is loaded into theouter cylinder from a stem of the spray valve and the inner cylinderthrough the check valve. Thereafter, the compressed gas in the interiorof the inner cylinder is purged to the exterior from the stem of thespray valve. Accompanying this process, the inner cylinder is in adeflated condition while on the other hand, the interior of the spatialportion of the outer cylinder maintains a condition in which compressedgas is loaded since the check valve is closed. Finally, the loadingprocess is completed by sequentially loading contents (concentrate) andcompressed gas to be dissolved into the contents from the spray valveinto the interior of the inner cylinder.

However, in a conventional aerosol product employing a double-chambercontainer, it is required to load compressed gas for making the innercylinder shrink in addition to compressed gas to be dissolved in thecontents, whereby the manufacturing becomes troublesome.

Moreover, since compressed gas needs to be loaded into the spatialportion between the inner cylinder and the outer cylinder in addition tocompressed gas to be dissolved in the contents to obtain a desiredpressure for the product, it is presented a drawback that the loadingamount of contents loaded into the inner cylinder with respect to theinner volume of the outer cylinder is only approximately 60% which isthe same level as in the case of a single-walled can.

In the former TN loading method in which compressed gas is loaded intothe inner sack through the stem, the space of the interior of the innersack is smaller compared to the space of the outer cylinder so that theloading pressure at the time of loading a specified amount of compressedgas into the inner sack becomes high. This might result in a drawbackthat the inner sack would burst.

On the other hand, while TN loading might also be performed in thelatter loading method, loading of the inner sack might be performedwherein the compressed gas to be dissolved into the contents(concentrate) is preliminarily dissolved and/or mixed into the contents.This, however, would require the provision of an exterior tank fordissolving and mixing purposes.

Further, in a conventional aerosol product employing a double-chambercontainer, it is often the case that the contents are in a non-foamedcondition (that is, compressed gas (propellant) is not sufficientlydissolved into the contents (concentrate)) so that such products areunsuitable for contents containing a large amount of resin such as resinfor hairdressing purposes which is apt to be choked at the stem.

The present invention has been made for the purpose of solving the aboveproblems, and it is an object of the present invention to provide anaerosol product and a method for manufacturing the same wherein thepressure of the product can be made low and the product can be easilymanufactured. It is another object of the present invention to providean aerosol product wherein the loading amount of the contents can beincreased compared to conventional products.

DISCLOSURE OF THE INVENTION

The aerosol product according to the present invention is an aerosolproduct comprising a double-chamber container separated by a movablepartition capable of dividing contents therewith, one spatial portionthereof being loaded with contents to be discharged and the otherspatial portion being loaded with compressed gas for pressurizing,characterized in that the compressed gas is a mixed compressed gas of atleast two types of mixed gas, in that at least a part of the partitionpresents permeability of the compressed gas, and in that the mixedcompressed gas selectively permeates the partition to be dissolved inthe contents to be ready for discharge.

It is preferable that the compressed gas for pressurizing is a mixed gasincluding a compressed gas of which Ostwald coefficient is not less than0.5 with respect to the contents at a temperature of 25° C. and a secondcompressed gas of which Ostwald coefficient is not more than 0.3.

It is preferable that the contents include water, monovalent alcohol ora mixed liquid thereof, that the first compressed gas is carbonic acidgas, and that the second compressed gas is nitrogen.

It is preferable that the partition is made of olefin group resin,especially of polyethylene or polypropylene.

It is preferable that the partition is a piston provided to be slidablebetween an inner surface of the exterior container, wherein a materialfor the piston is polyester, vinyl chloride resin, ABS resin or nylon.

The method for manufacturing an aerosol product according to the presentinvention is a method for manufacturing an aerosol product employing adouble-chamber container separated by a movable partition of which atleast a part presents gas permeability, and which is capable ofseparating contents therewith, characterized in that the method includesthe steps of

(a) loading contents to be discharged into one spatial portion of adouble-chamber container interior,

(b) loading a mixed compressed gas for pressurizing including at leasttwo types of mixed gas into the other spatial portion of thedouble-chamber container interior, and

(c) dissolving the mixed compressed gas into the contents afterselectively making the gas permeate the partition.

It is preferable that the method for manufacturing an aerosol productemploy, as the double-chamber container, an aerosol container in which aspray valve is fitted onto an outer cylinder accommodating therein agas-permeable inner cylinder, and includes the steps of

(a) loading the contents into the inner cylinder,

(b) loading the mixed compressed gas into a spatial portion providedbetween the outer cylinder and the inner cylinder, and

(c) dissolving the mixed compressed gas into the contents afterselectively making the gas permeate the inner cylinder.

It is preferable that the method for manufacturing an aerosol productemploy, as the double-chamber container, a piston-type aerosol containerhaving a cylindrical exterior container, a piston provided in theexterior container to be slidable with respect to an inner surface ofthe exterior container, and an upper chamber and a lower chamber formedby being separated by the piston within the exterior container, whereina spray valve is fitted onto an open end of the outer cylinder, andincludes the steps of

(a) loading contents into either of the upper chamber and lower chamber,

(b) loading compressed gas into an interior of the other of the upperchamber and lower chamber, and

(c) dissolving the mixed compressed gas into the contents afterselectively making the gas permeate the piston.

In the aerosol product of the present invention, there is employed agas-permeable partition as a partition (inner cylinder, piston) forseparating the interior of the double-chamber into two spatial portionswherein one of the spatial portions is loaded with contents to bedischarged, while the other one of the spatial portions is loaded withcompressed gas for pressurizing and retained. In this manner, the mixedcompressed gas is selectively made to permeate the partition to bedissolved into the contents so that manufacturing is made easy.

Further, since the aerosol product according to the present inventionemploys a double-chamber container provided with a partition such as aninner sack, the degree of pressure descent is smaller than comparedthose of aerosol products employing a conventional single type containerwith no inner sack, so that the pressure of the final product can bemade low.

Also, since the compressed gas to be dissolved into the contents ismixed compressed gas kept in a spatial portion between the innercylinder and the outer cylinder and is used in a selective manner, thecompressed gas can be suitably selected to be, for instance, a mixed gasof a first compressed gas of which Ostwald coefficient with respect tothe contents is not less than 0.5 at a temperature of 25° C. (e.g.carbonic acid gas) and a second compressed gas of which Ostwaldcoefficient is not more than 0.3 (e.g. nitrogen). With this arrangement,it is enabled to make the first compressed gas is mainly made topermeate the inner cylinder and is dissolved in the contents while thesecond compressed gas which is hardly soluble into the contents ismainly used for pressurizing the inner cylinder. In this case, only thefirst compressed gas (carbonic acid gas) is dissolved into the contents(while the second compressed gas (nitrogen) is included in the exteriorof the inner cylinder) so that gas drifting that occurs after the spraycan be made small and gas withdrawal of the first compressed gas at thetime of spray can be prevented, whereby the pressure descent can be madesmall. In this manner, the loading amount for the contents can besecured to be approximately 70% of the inner volume of the outercylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional explanatory view showing one embodiment of anaerosol product according to the present invention;

FIG. 2 is a sectional explanatory view showing a condition after sprayof the aerosol product of FIG. 1;

FIG. 3 is a graph showing pressure variations of mixed compressed gas inthe interior of the spatial portion of the aerosol product of FIG. 1;

FIG. 4 is a sectional explanatory view showing another embodiment of theaerosol product according to the present invention;

FIG. 5 is a sectional explanatory view showing still another embodimentof the aerosol product according to the present invention; and

FIG. 6 is a sectional explanatory view showing yet another embodiment ofthe aerosol product according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The aerosol product according to the present invention will now beexplained in details with reference to the drawings. FIG. 1 is asectional explanatory view showing one embodiment of an aerosol productaccording to the present invention, FIG. 2 is a sectional explanatoryview showing a condition after spray of the aerosol product of FIG. 1,FIG. 3 is a graph showing pressure variations of mixed compressed gas inthe interior of the spatial portion of the aerosol product of FIG. 1,FIG. 4 is a sectional explanatory view showing another embodiment of theaerosol product according to the present invention, FIG. 5 is asectional explanatory view showing still another embodiment of theaerosol product according to the present invention, and FIG. 6 is asectional explanatory view showing still another embodiment of theaerosol product according to the present invention.

The aerosol container shown in FIG. 1 employs a flexible inner cylinder1 as a partition, the container being a so-called double-chamberpressurizing container wherein contents A in an interior of thegas-permeable inner cylinder 1 is forced out by compressed gas B in aninterior of a spatial portion 7 provided between the inner cylinder 1and an outer cylinder 2. A mounting cup 4 for supporting a spray valve 3is fitted in a sealing manner onto the outer cylinder 2 whichaccommodates therein the inner cylinder 1. A button 20 is fitted to avalve stem 6.

The aerosol container as shown in FIG. 1 is further provided with a gasejecting tool 9 at a lower portion of a valve housing 5 which piercesthrough the inner cylinder 1 in case the contents A within the innercylinder 1 is decreased to be less than a specified amount so that thecompressed gas B in the spatial portion 7 can be reliably discharged tothe exterior of the container through the valve stem 6 of the sprayvalve 3. The gas ejecting tool 9 includes, at a peripheral portionthereof, a triangular tip-sharpened extrusion 8 having a sharpened tip 8a and which is inclined towards an inner wall of the inner cylinder 1. Adischarge conduit 10 is supported at a bottom portion of thetip-sharpened extrusion 8 for introducing the contents A into the sprayvalve 3.

The inner cylinder 1 is made of a material having gas-permeability andwhich is capable of dividing the contents (that is, which issubstantially not permeable with respect to the contents). It ispreferable that the inner cylinder 1 is made of olefin group resin thatis superior in terms of resistivity with respect to chemicals such asacid or alkali and is also superior in terms of gas-permeability,wherein polypropylene (PP) or polyethylene (PE) is especially preferablein terms of low costs.

Compressed gas B is loaded into the interior of the spatial portion 7and dissolved into contents A by permeating, in a selective manner,through the inner cylinder 1 which presents gas-permeability. Loading ofthe compressed gas B might be performed through conventionally knownmethods as used for single-walled cans. In one example, the followingsteps might be performed: contents A (concentrate) is loaded into theinner cylinder 1; the spray valve 3 is mounted onto the outer cylinder2; thereafter, compressed gas which is mixed in a manner as will beexplained later is loaded into the spatial portion 7 through a clearancebetween the inner cylinder 1 and the outer cylinder 2; and finally, thespray valve 3 (more particularly, the mounting cup 4) is crimped. Thisis an unprecedented simple loading method for a double-chambercontainer.

The compressed gas B is composed of at least one sort of gas forpresenting two functions, that is, a first function of dissolving intothe contents A for making the contents A be sprayed in a form of finefoggy particles or be discharged in a foamed condition and a secondfunction of making the inner cylinder 1 shrink, and might be selectedfrom among carbonic acid gas (CO₂), nitrogen (N₂), oxygen (O₂), nitrousoxide (N₂O) or air etc. which are also used in conventional methods.While air is generally a mixture a nitrogen and oxygen, air is notconsidered to be a mixed gas. When compared to liquefied gas such as theabove-mentioned liquefied petroleum gas, the decrease in pressure at lowtemperature is smaller in case of using carbonic acid gas, nitrogen,oxygen, nitrous oxide or air. Therefore, pressure differences of thepressure of the inner cylinder interior and the pressure of the spatialportion 7 between the outer cylinder and the inner cylinder can be madesmall so that there is no fear that the inner cylinder 1 would burst.

Among these, it is preferable that the gas is a mixed gas of a firstcompressed gas having an Ostwald coefficient of not less than 0.5 withrespect to the contents A at a temperature of 25° C. and a secondcompressed gas having an Ostwald coefficient of not more than 0.3. Usingthis mixed gas, the first compressed gas might be mainly made permeatethe inner cylinder 1 and dissolved into contents A while the remaininggas which mainly includes the second compressed gas which is hardlysoluble in the contents (which is compressed gas B in FIG. 1) is usedfor shrinking the inner cylinder A. At this time, the degree of pressuredescent in the interior of the inner cylinder is smaller than comparedto a case in which the compressed gas includes only the first compressedgas (for instance, in case only carbonic acid gas is used as in theexample that will be explained later). With this arrangement, theloading amount for the contents can be secured to be approximately 70%of the inner volume of the outer cylinder.

The Ostwald coefficient of the first compressed gas should preferably beone presenting large solubility in order to present performance as acompressed gas or to act as a foaming agent and should preferably be notless than 0.5. On the other hand, the Ostwald coefficient of the secondcompressed gas should preferably be one presenting small solubility inorder to act as a pressurizing agent and should preferably be not morethan 0.3.

The mixing ratio of the first compressed gas and the second compressedgas should preferably be in the range of approximately 10-90:90-10 andfurther in the range of 20-80:80-20.

In case compressed gas having an Ostwald coefficient of not less than0.5 is dissolved into the contents, the following three effects can beachieved.

(1) Minute foaming objects can be obtained.

Taking an example in which the compressed gas to be dissolved intocontents including foaming components has an Ostwald coefficient of 2, 2ml of compressed gas is dissolved per 1 ml of contents (concentrate)when the pressure is 0.1 MPa. Thus, in case the pressure is 0.3 MPa,approximately 6 ml is dissolved (that is, compressed gas correspondingto 5 to 10 times the volume of the concentrate is dissolved). Especiallyin case of LPG (liquefied petroleum gas), its foaming specific gravity(weight of foaming objects per unit volume) is 0.03 to 0.05. Thus, afoaming object having a volume that is 30 to 20 times the volume of theconcentrate can be obtained. In a foaming object including dissolvedcompressed gas, gas within a liquid film is smaller than in a foamingobject obtained with liquefied gas so that it contains therein quite alarge amount of minute foams (minute foaming object).

Since such a minute foaming object can be obtained, contents remainingin the interior of the stem is also sufficiently foamed than compared tonon-foamed objects so that its density is also very small. Thus, only asmall amount of resin which is contained in the contents sticks to thepath so that the path is not apt to be choked. Consequently, thedouble-chamber container can suitably used also for contents containinga large amount of resin which is apt to choking such as resin forhairdressing purposes.

(2) Minute particles can be obtained.

In case compressed gas having an Ostwald coefficient of not less than0.5 is dissolved into contents which does not include foamingcomponents, the compressed gas which has been dissolved by a largeamount is rapidly discharged from the contents so that the contents tobe sprayed can be sprayed in a form of minute particles.

(3) pH adjustments can be performed.

In case of employing carbonic acid gas as a compressed gas having anOstwald coefficient of not less than 0.5, the dissolution of carbonicacid gas into the contents will result in a shift towards an acidcondition so that pH of the contents might be desirably adjusted.Consequently, it can be presented for circulation promoting effects ofthe contents (reference should be made to Japanese Examined PatentPublication No. 47684/1988).

For particularly selecting the compressed gas B, the solubility ofcarbonic acid gas (CO₂), nitrogen (N₂), oxygen (O₂), nitrous oxide (N₂O)and air with respect to a solvent of water-ethyl alcohol group, which isconventionally used for general aerosol products, is tested. Table 1shows values of solubility of each of the gases with respect to water ata temperature of 25° C. and values of solubility with respect to ethylalcohol (it should be noted that the Ostwald coefficient of air withrespect to ethyl alcohol is an actually measured value).

TABLE 1 CO₂ N₂ O₂ N₂O Air Water 0.759 0.0143 0.0283 0.575 0.0167 EthylAlcohol 2.94 0.143 0.220 2.09 0.158

It can be understood from Table 1 that the first compressed gas havingan Ostwald coefficient of not less than 0.5 at a temperature of 25° C.includes carbonic acid gas and nitrous oxide, while the secondcompressed gas of which Ostwald coefficient is not more than 0.3includes nitrogen, oxygen and air. Among these, especially a mixed gasof carbonic acid gas and nitrogen is most preferable in view ofstability (of container, contents etc.) of the aerosol product.

As a reference, values of critical temperature for each of the carbonicacid gas, nitrogen, oxygen, nitrous oxide, and air are shown in Table 2.It should be noted that a critical temperature is a temperature at whichno liquefaction is enabled upon applying a high pressure but merely ahighly densified gas is generated.

TABLE 2 Critical Temperature (° C.) CO₂ 31.1 N₂ −147.0 O₂ −118.4 N₂O36.5 Air −140.7

It can be understood from Table 2 that there exists a correlationbetween the Ostwald coefficient and the critical temperature. Thus, uponcomparing Tables 1 and 2, the first compressed gas might be defined tobe a gas having a critical temperature which is in the range of 0 to 50°C. and the second compressed gas might be defined to be a gas having acritical temperature which is not more than −100° C.

For manufacturing an aerosol product as shown in FIG. 1, the contents Ais first loaded into the gas-permeable inner cylinder 1 of FIG. 1, and amixed compressed gas B is then loaded into the spatial portion 7 betweenthe outer cylinder 2 and the inner cylinder 1 and is retainedthereafter. By retaining it for a specified time, the mixed compressedgas B can be selectively made permeate the inner cylinder 1 to bedissolved into the contents A so that easy manufacturing is enabled.Moreover, since there is no need to load compressed gas into an innersack (which corresponds to the inner cylinder 1 of the presentembodiment) by applying a large loading pressure as it was necessary inprior art loading methods, there is no fear that the inner sack isburst. Further, there is no need to provide for a tank for dissolvingand mixing purposes.

Since the aerosol product of FIG. 1 employs a double-chamber containerhaving an inner cylinder 1, the danger of misuse is eliminated thancompared to conventional aerosol products employing a single-walled canwhich is not provided with an inner cylinder, while the degree ofpressure descent is small so that the internal pressure of the finalproduct can be made low. For instance, compared to a pressure ofapproximately 0.2 MPa in a final product employing a single-walled can,a desired condition for spray can be maintained for a product ofdouble-chamber type as shown in FIG. 1 when the internal pressure of thefinal product is not less than 0.07 MPa, and preferably, not less than0.1 MPa.

In case the compressed gas B includes only carbonic acid gas of whichsolubility is relatively large, the gas is well dissolved into thecontents A and foamed portions thereof are ejected at the time of sprayso that the degree of pressure descent after the spray is large. Hence,it is necessary to set the initial pressure somewhat higher in view ofthe final condition of spray (approximately 0.15 MPa which is still byfar smaller than the pressure of 0.2 MPa of a final product employing asingle-walled can). Moreover, in case the pressure is decreasedaccompanying the deflating of the inner cylinder after spray as shown inFIG. 2, carbonic acid gas that has dissolved into the contents A acts torecover the original shape so that a gas drift is generated at an upperportion of the inner cylinder 1, thereby only gas is sprayed withoutbeing accompanied by the contents A at the time of performing thefollowing spray (so-called gas withdrawal occurs), resulting in a lossof gas.

Therefore, by employing the above-described mixed gas including a firstcompressed gas such as carbonic acid gas and a second compressed gassuch as nitrogen, almost all of the nitrogen will remain at the spatialportion 7 at the exterior of the inner cylinder 1 so that the degree ofpressure descent after spray can be made small and gas drifts are hardlygenerated. Thus, it can be presented for an effect that the initialpressure can be set low and hardly any loss of gas is caused.

In one embodiment, 100 g of refined water was loaded into an inner sackmade of gas-permeable resin and the mixed compressed gases shown inTable 3 were respectively loaded into a spatial portion between ametallic container and the inner sack. Pressure variations of the mixedcompressed gases in the interior of the spatial portion were measuredimmediately after the loading and at respective elapsed times.

As can be understood from Table 3 and the graph of FIG. 3 correspondingto Nos. I-VI of Table 3, while both compressed gases permeate the innercylinder (the particle size of nitrogen gas being smaller than that ofcarbonic acid gas), differences in the Ostwald coefficient resulted in aselective dissolution of CO₂.

TABLE 3 Kind of Mixed Immediately Compressed After 24 36 60 100 330 GasLoading 1 Hour 2 Hours 3 Hours 5 Hours 8 Hours Hours Hours Hours HoursHours No. (% by weight) (Mpa) Later Later Later Later Later Later LaterLater Later Later I N₂/CO₂ = 100/0 0.719 0.719 0.717 0.717 0.713 0.7080.700 0.694 0.690 0.685 0.677 II N₂/CO₂ = 80/20 0.709 0.706 0.700 0.6910.682 0.665 0.617 0.594 0.572 0.563 0.549 III N₂/CO₂ = 60/40 0.708 0.7030.694 0.681 0.665 0.642 0.565 0.532 0.496 0.479 0.458 IV N₂/CO₂ = 40/600.702 0.697 0.685 0.673 0.655 0.628 0.535 0.497 0.459 0.441 0.420 VN₂/CO₂ = 20/80 0.703 0.696 0.683 0.666 0.644 0.611 0.495 0.451 0.4000.377 0.352 VI N₂/CO₂ = 0/100 0.698 0.682 0.665 0.641 0.611 0.563 0.3960.331 0.249 0.210 0.172

Next, an aerosol product employing a piston as a partition will beexplained.

The aerosol product shown in FIG. 4 comprises a cylindrical exteriorcontainer 11 and a gas-permeable piston 12 which is provided to beslidable between an inner surface of the exterior container 11, andwhich is capable of dividing contents (that is, which is substantiallynot permeable of the contents). Within the exterior container 11, thereare formed an upper chamber 13 and a lower chamber 14 by being separatedby the piston 12. A mounting cup 16 for supporting a spray valve 15 isfitted in a sealing manner onto an open end at an upper portion of theexterior container 11. Note that reference numeral 20 denotes a button.

The contents A to be discharged is loaded into the upper chamber 13while the compressed gas B is loaded into the lower chamber 14. Themixed compressed gas B in the lower chamber 14 is dissolved intocontents A by permeating, in a selective manner, the gas-permeablepiston 12.

A gas-permeable resin used for the piston 12 is not especially limitedso long as it presents superior gas-permeability and pressure resistancein addition to slidability. Representative examples of suchgas-permeable resin are, for instance, polyethylene, polypropylene,polyester, vinyl chloride resin, ABS resin or polyamide represented bynylon. Such gas-permeable resin might be used either in a single stateor as a laminated body.

The piston 12 might either be a molded article formed through blowmolding method, or alternatively, a molded article formed throughinjection molding method. Further, while the configuration of the piston12 is not especially limited, a representative configuration thereof iscylindrical. Although the thickness for the piston 12 cannot beexplicitly determined since it is varied by the sort of gas-permeableresin which composes the piston 12, it is preferable that the thicknessis in the range of approximately 0.5 to 2 mm to ensure sufficientpressure resistance and gas-permeability.

For manufacturing the aerosol product shown in FIG. 4, mixed compressedgas is first loaded into an upper chamber 13 and lower chamber 14. Bysimply performing loading of mixed compressed gas into the upperchamber, the gas can be also loaded into the lower chamber 13 since alateral side of the piston 12 (a portion at which it contacts an innersurface of exterior container 11) is bent at the time of performing gasloading. After purging mixed compressed gas in the interior of the upperchamber 13, contents A is loaded into the upper chamber 13. Afterretaining it for a specified time, a part of the compressed gas B ismade to permeate the piston 12 to be dissolved in the contents A so thateasy manufacturing is enabled. Moreover, since it is not necessary toload compressed gas by applying a large loading pressure, there is nofear that the piston is damaged, and it is also not necessary to providefor a tank for dissolving and mixing purposes.

It should be noted that while FIG. 4 shows an example in which contentsA are loaded into the upper chamber 13 and compressed gas B into thelower chamber 13, the present invention is not limited to this. Forinstance, in an alternative example of an aerosol product employing apiston as a partition shown in FIG. 5, contents A are loaded into lowerchamber 14 and compressed gas B into upper chamber 13, wherein the lowerchamber 14 is connected to a spray valve 15 through a tube 18 piercingthrough the gas-permeable piston 12 with which similar effects as theabove-described effects might be obtained. Note that reference numeral20 denotes a button.

Further, similar effects might also be achieved with an aerosol productshown in FIG. 6 wherein both of the above-described gas-permeable innercylinder 1 and the piston 12 are employed as a partition. It should benoted that in the case shown in FIG. 6, contents A are loaded into theinner cylinder 1 and the lower chamber 14 while compressed gas B isloaded into the upper chamber 13. Note that reference numeral 20 denotesa button.

The above-described aerosol product of double-chamber type including agas-permeable partition might be applied for cleaning agents (seeJapanese Unexamined Patent Publication No. 243900/1986), Cologne waterfor the body (see Japanese Unexamined Patent Publication No.141910/1988), hair restoration agents (see Japanese Unexamined PatentPublication No. 141917/1988), antipruritic agents (see JapaneseUnexamined Patent Publication No. 141918/1988), patches of externalpreparation (see Japanese Unexamined Patent Publication No.230514/1989), adhesives (see Japanese Unexamined Patent Publication No.9971/1991), antiperspiration agents (see Japanese Unexamined PatentPublication No. 148212/1991), hot foams (see Japanese Unexamined PatentPublication No. 264186/1992), antiphlogistic analgesic (see JapaneseUnexamined Patent Publication No. 279250/1993), oral agents (seeJapanese Unexamined Patent Publication No. 345026/1993), toothpaste (seeJapanese Unexamined Patent Publication No. 55659/1994, No. 42218/1995),sterilizing disinfectants (see Japanese Unexamined Patent PublicationNo. 327750/1994), hair-care articles (see Japanese Unexamined PatentPublication No. 206648/1995), and skin-care articles (see JapaneseUnexamined Patent Publication No. 330540/1995).

The aerosol product according to the present invention employs agas-permeable partition for a double-chamber container, whereby mixedcompressed gas can be selectively made to permeate the partition to bedissolved into contents so that the manufacturing thereof is made easy.Moreover, since it is not required to perform loading of compressed gasby applying a large loading pressure, there is no fear that thepartition is damaged. There is also no necessity to provide for a tankfor dissolving and mixing purposes.

Employing a double-chamber container, it is enabled to provide anaerosol product of which pressure of the final product is made lowcompared to conventional aerosol products which are not equipped with aninner sack.

In case of utilizing a mixed gas including a first compressed gas ofwhich Ostwald coefficient with respect to the contents is not less than0.5 at a temperature of 25° C. and a second compressed gas which Ostwaldcoefficient is not more than 0.3 as the compressed gas, the degree ofpressure descent of the interior of a spatial portion accommodatingtherein the contents is made small whereby it is achieved to secure aloading amount for the contents that is larger than those ofconventional products.

INDUSTRIAL APPLICABILITY

The aerosol product according to the present invention employs agas-permeable partition for a double-chamber container, whereby mixedcompressed gas can be selectively made to permeate the partition to bedissolved into contents so that the manufacturing thereof is made easy.Moreover, since it is not required to perform loading of compressed gasby applying a large loading pressure, there is no fear that thepartition is damaged. There is also no necessity to provide for a tankfor dissolving and mixing purposes so that it is useful as an aerosolproduct using a double-chamber type container.

What is claimed is:
 1. An aerosol product comprising a double-chambercontainer separated by a movable partition capable of dividing contentstherewith, one spatial portion thereof being loaded with contents to bedischarged and the other spatial portion being loaded with compressedgas for pressurizing, wherein the compressed gas is a mixed compressedgas of at least two types of mixed gas, at least a part of the partitionpresents permeability of the compressed gas, the mixed compressed gasselectively permeates the partition to be dissolved in the contents tobe ready for discharge, and the compressed gas for pressurizing is amixed gas including a compressed gas of which Ostwald coefficient is notless than 0.5 with respect to the contents at a temperature of 25° C.and a second compressed gas of which Ostwald coefficient is not morethan 0.3.
 2. The aerosol product of claim 1, wherein the contentsinclude water, monovalent alcohol or a mixed liquid thereof, the firstcompressed gas is carbonic acid gas, and the second compressed gas isnitrogen.
 3. The aerosol product of any one of claims 1 or 2, whereinthe partition is made of olefin group resin.
 4. The aerosol product ofclaim 3, wherein the partition is made of one of polyethylene andpolypropylene.
 5. The aerosol product of any one of claims 1 or 2,wherein the partition is a piston provided to be slidable between aninner surface of the exterior container, wherein a material for thepiston is polyester, vinyl chloride resin, ABS resin or nylon.
 6. Amethod for manufacturing an aerosol product employing a double-chambercontainer separated by a movable partition of which at least a partpresents gas permeability, and which is capable of separating contentstherewith, the method including the steps of (a) loading contents to bedischarged into one spatial portion of a double-chamber containerinterior, (b) loading a mixed compressed gas for pressurizing at leasttwo types of mixed gases into the other spatial portion of thedouble-chamber container interior, and (c) dissolving the mixedcompressed gas into the contents after selectively making the gaspermeate the partition, and in that the compressed gas for pressuring isa mixed gas including a compressed gas of which Ostwald coefficient isnot less than 0.5 with respect to the contents at a temperature of 25°C. and a second compressed gas of which Ostwald coefficient is not morethan 0.3.
 7. The method of claim 6, wherein the method for manufacturingan aerosol product employs, as the double-chamber container, an aerosolcontainer in which a spray valve is fitted onto an outer cylinderaccommodating therein a gas-permeable inner cylinder, and includes thesteps of (a) loading the contents into the inner cylinder, (b) loadingthe mixed compressed gas into a spatial portion provided between theouter cylinder and the inner cylinder, and (c) dissolving the mixedcompressed gas into the contents after selectively making the gaspermeate the inner cylinder.
 8. The method of claim 6, wherein themethod for manufacturing an aerosol product employs, as thedouble-chamber container, a piston-type aerosol container having acylindrical exterior container, a piston provided in the exteriorcontainer to be slidable with respect to an inner surface of theexterior container, and an upper chamber and a lower chamber formed bybeing separated by the piston within the exterior container, wherein aspray valve is fitted onto an open end of the outer cylinder, andincludes the steps of (a) loading contents into either of the upperchamber and lower chamber, (b) loading compressed gas into an interiorof the other of the upper chamber and lower chamber, and (c) dissolvingthe mixed compressed gas into the contents after selectively making thegas permeate the piston.